Available on Commodore Vic 20 computers. On the left side.
1 TOP 22 +-------------------//----------------+ | =================//================ | +-----------------//------------------+ A BOTTOM Z
 (at the Computer)
 (at the Computer)
UNKNOWN CONNECTOR at the Computer.
| Pin | Name | Description | 
|---|---|---|
| A | GND | Ground | 
| B | CA0 | Address 0 | 
| C | CA1 | Address 1 | 
| D | CA2 | Address 2 | 
| E | CA3 | Address 3 | 
| F | CA4 | Address 4 | 
| H | CA5 | Address 5 | 
| J | CA6 | Address 6 | 
| K | CA7 | Address 7 | 
| L | CA8 | Address 8 | 
| M | CA9 | Address 9 | 
| N | CA10 | Address 10 | 
| P | CA11 | Address 11 | 
| R | CA12 | Address 12 | 
| S | CA13 | Address 13 | 
| T | I/O 2 | Decoded I/O block 2, starting at $9130 | 
| U | I/O 3 | Decoded I/O block 3, starting at $9140 | 
| V | S02 | Phase 2 System Clock | 
| W | /NMI | Non maskable Interrupt | 
| X | /RESET | 6502 Reset | 
| Y | n/c | Not connected | 
| Z | GND | Ground | 
| 1 | GND | Ground | 
| 2 | CD0 | Data 0 | 
| 3 | CD1 | Data 1 | 
| 4 | CD2 | Data 2 | 
| 5 | CD3 | Data 3 | 
| 6 | CD4 | Data 4 | 
| 7 | CD5 | Data 5 | 
| 8 | CD6 | Data 6 | 
| 9 | CD7 | Data 7 | 
| 10 | /BLK 1 | BLK 1 (Memory location $2000 - $3fff) | 
| 11 | /BLK 2 | BLK 2 (Memory location $4000 - $5fff) | 
| 12 | /BLK 3 | BLK 3 (Memory location $6000 - $7fff) | 
| 13 | /BLK 5 | BLK 5 (Memory location $a000 - $bfff) | 
| 14 | RAM 1 | RAM 1 (Memory location $0400 - $07ff) | 
| 15 | RAM 2 | RAM 2 (Memory location $0800 - $0bff) | 
| 16 | RAM 3 | RAM 3 (Memory location $0c00 - $0fff) | 
| 17 | V R/W | Read/Write from Vic chip (1=R, 0=W) | 
| 18 | C R/W | Read/Write from CPU (1=R, 0=W) | 
| 19 | /IRQ | 6502 Interrupt Request | 
| 20 | n/c | Not connected | 
| 21 | +5V | +5 VDC | 
| 22 | GND | Ground | 
| Contributor: | Joakim Ögren | 
| Source: | Inside your Vic 20 by Ward Shrake | 
| "The Vic Revealed" by Nick Hampshire, 1982, Hayden Book Co, Inc. | |
| "Vic20 Programmer's Reference Guide", 1992, Commodore Business, Machines, Inc. and Howard W. Sams & Company, Inc. | 
  Copyright © The Hardware Book Team 1996-2004.
  May be copied and redistributed, partially or in whole, as appropriate.
  Document last modified: 2002-01-10